recommend a free or inexpensive sun hat pattern/tutorial?

im sure i can find a few free patterns and tutorials on sun hats, but was wondering if anyone likes/recommends a certain one?

im looking for something that would fit older toddlers. Both my LOs have huge heads (above 95th percentile) so I think they'd need something that fits a 3T size.. I like the kind with a flap that protects the neck in the back.